<!DOCTYPE html>
<html lang="en-US">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>JS中防抖与节流的讲解与封装 | 爆米花小布</title>
    <meta name="generator" content="VuePress 1.9.7">
    <link rel="icon" href="/favicon.ico">
    <script defer="defer" async="async" src="//cpro.baidustatic.com/cpro/ui/cm.js"></script>
    <meta name="description" content=" ">
    
    <link rel="preload" href="/assets/css/0.styles.54de4a22.css" as="style"><link rel="preload" href="/assets/js/app.36e8cb25.js" as="script"><link rel="preload" href="/assets/js/2.cd8e88cf.js" as="script"><link rel="preload" href="/assets/js/25.260c7616.js" as="script"><link rel="prefetch" href="/assets/js/10.5a175a73.js"><link rel="prefetch" href="/assets/js/11.7c8d5810.js"><link rel="prefetch" href="/assets/js/12.c77aca0d.js"><link rel="prefetch" href="/assets/js/13.fc475cb0.js"><link rel="prefetch" href="/assets/js/14.517ed6e7.js"><link rel="prefetch" href="/assets/js/15.7dc9cc39.js"><link rel="prefetch" href="/assets/js/16.4223237a.js"><link rel="prefetch" href="/assets/js/17.0e3dcd26.js"><link rel="prefetch" href="/assets/js/18.132512c7.js"><link rel="prefetch" href="/assets/js/19.55275db3.js"><link rel="prefetch" href="/assets/js/20.621b52a1.js"><link rel="prefetch" href="/assets/js/21.daa66e46.js"><link rel="prefetch" href="/assets/js/22.537fd259.js"><link rel="prefetch" href="/assets/js/23.81c79725.js"><link rel="prefetch" href="/assets/js/24.ee80a08c.js"><link rel="prefetch" href="/assets/js/26.03e10148.js"><link rel="prefetch" href="/assets/js/27.768e5af1.js"><link rel="prefetch" href="/assets/js/28.ad0f08eb.js"><link rel="prefetch" href="/assets/js/29.9e188b97.js"><link rel="prefetch" href="/assets/js/3.9cba588d.js"><link rel="prefetch" href="/assets/js/30.f2aa9a7c.js"><link rel="prefetch" href="/assets/js/31.93c74095.js"><link rel="prefetch" href="/assets/js/32.4735eb89.js"><link rel="prefetch" href="/assets/js/33.7b05518b.js"><link rel="prefetch" href="/assets/js/34.3db00b39.js"><link rel="prefetch" href="/assets/js/35.ea9a0227.js"><link rel="prefetch" href="/assets/js/36.5873bde7.js"><link rel="prefetch" href="/assets/js/37.2cbd5350.js"><link rel="prefetch" href="/assets/js/38.6c2de9e4.js"><link rel="prefetch" href="/assets/js/39.d3c0116f.js"><link rel="prefetch" href="/assets/js/4.97aec80c.js"><link rel="prefetch" href="/assets/js/40.47b05f9f.js"><link rel="prefetch" href="/assets/js/41.5dfb852e.js"><link rel="prefetch" href="/assets/js/42.1d7cf4c2.js"><link rel="prefetch" href="/assets/js/43.43f59d94.js"><link rel="prefetch" href="/assets/js/44.19309bf6.js"><link rel="prefetch" href="/assets/js/45.dbee3f0a.js"><link rel="prefetch" href="/assets/js/46.a373745d.js"><link rel="prefetch" href="/assets/js/5.bc4ebf1d.js"><link rel="prefetch" href="/assets/js/6.805bb5f3.js"><link rel="prefetch" href="/assets/js/7.9724c5a3.js"><link rel="prefetch" href="/assets/js/8.6c6d5662.js"><link rel="prefetch" href="/assets/js/9.641efeda.js">
    <link rel="stylesheet" href="/assets/css/0.styles.54de4a22.css">
  </head>
  <body>
    <div id="app" data-server-rendered="true"><div class="theme-container"><header class="navbar"><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/" class="home-link router-link-active"><!----> <span class="site-name">爆米花小布</span></a> <div class="links"><div class="search-box"><input aria-label="Search" autocomplete="off" spellcheck="false" value=""> <!----></div> <nav class="nav-links can-hide"><div class="nav-item"><a href="/" class="nav-link">
  主页
</a></div><div class="nav-item"><a href="/element-ui/el-table-select-all/" class="nav-link">
  前端博客
</a></div><div class="nav-item"><a href="https://shenxiaobu.github.io/vue-element-dict/" target="_blank" rel="noopener noreferrer" class="nav-link external">
  PC端字典插件包
  <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div><div class="nav-item"><a href="https://shenxiaobu.github.io/vue-vant-dict" target="_blank" rel="noopener noreferrer" class="nav-link external">
  移动端字典插件包
  <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div> <!----></nav></div></header> <div class="sidebar-mask"></div> <aside class="sidebar"><nav class="nav-links"><div class="nav-item"><a href="/" class="nav-link">
  主页
</a></div><div class="nav-item"><a href="/element-ui/el-table-select-all/" class="nav-link">
  前端博客
</a></div><div class="nav-item"><a href="https://shenxiaobu.github.io/vue-element-dict/" target="_blank" rel="noopener noreferrer" class="nav-link external">
  PC端字典插件包
  <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div><div class="nav-item"><a href="https://shenxiaobu.github.io/vue-vant-dict" target="_blank" rel="noopener noreferrer" class="nav-link external">
  移动端字典插件包
  <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div> <!----></nav>  <ul class="sidebar-links"><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>Element-ui组件使用经验</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/element-ui/el-table-select-all/" class="sidebar-link">使用el-table实现全选功能</a></li><li><a href="/element-ui/el-table-sku/" class="sidebar-link">利用element实现sku规格相关功能</a></li><li><a href="/element-ui/el-cropper/" class="sidebar-link">利用vue-cropper实现图片裁剪功能</a></li><li><a href="/element-ui/el-form-nesting/" class="sidebar-link">el-form嵌套表单校验</a></li><li><a href="/element-ui/el-theme/" class="sidebar-link">使用element-ui组件库实现主题切换功能</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading open"><span>JS必备知识</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/JS/call-apply-bind/" class="sidebar-link">js中的call、apply和bind</a></li><li><a href="/JS/debounce-throttle/" aria-current="page" class="active sidebar-link">JS中防抖与节流的讲解与封装</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/JS/debounce-throttle/#防抖" class="sidebar-link">防抖</a></li><li class="sidebar-sub-header"><a href="/JS/debounce-throttle/#节流" class="sidebar-link">节流</a></li></ul></li><li><a href="/JS/tree-data/" class="sidebar-link">JS中树形结构数据相关方法</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>CSS实战经验</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/CSS/contour-layout/" class="sidebar-link">css实现等高布局</a></li><li><a href="/CSS/fixed-aspect-ratio/" class="sidebar-link">css实现固定宽高比</a></li><li><a href="/CSS/draw-triangle/" class="sidebar-link">CSS画一个三角形</a></li><li><a href="/CSS/draw-ring/" class="sidebar-link">CSS画一个环形进度条</a></li><li><a href="/CSS/pseudo-class/" class="sidebar-link">伪类和伪元素的区别与使用</a></li><li><a href="/CSS/clear-float/" class="sidebar-link">清除浮动的原理与时机</a></li><li><a href="/CSS/layout/" class="sidebar-link">三栏布局问题（左右固定宽度 中间自适应）</a></li><li><a href="/CSS/flex/" class="sidebar-link">flex布局祥解</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>实用的npm包</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/npm/xiaobu-pic-zoom/" class="sidebar-link">xiaobu-pic-zoom图片放大镜</a></li><li><a href="/npm/vue-message-code/" class="sidebar-link">vue-message-code短信验证码</a></li><li><a href="/npm/xiaobu-water-marker/" class="sidebar-link">xiaobu-water-marker水印</a></li><li><a href="/npm/vue-flutter/" class="sidebar-link">vue-flutter漂浮动画</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>VUE小妙招</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/vue-config/search-menu/" class="sidebar-link">利用fuse.js实现搜索菜单功能</a></li><li><a href="/vue-config/alias/" class="sidebar-link">vue项目配置别名</a></li><li><a href="/vue-config/svg-sprite-loader/" class="sidebar-link">vue项目配置使用svg图标</a></li><li><a href="/vue-config/vue-mode-env/" class="sidebar-link">vue项目的模式和环境变量</a></li><li><a href="/vue-config/system-config/" class="sidebar-link">vue项目配置系统变量</a></li><li><a href="/vue-config/axios-optimization-one/" class="sidebar-link">vue项目axios请求优化（一）</a></li><li><a href="/vue-config/axios-optimization-two/" class="sidebar-link">vue项目axios请求优化（二）</a></li><li><a href="/vue-config/axios-optimization-three/" class="sidebar-link">vue项目axios请求优化（三）</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>前端工具</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/tool/use-nvm/" class="sidebar-link">nvm的使用</a></li><li><a href="/tool/vscode/sftp/" class="sidebar-link">vscode插件之sftp</a></li><li><a href="/tool/vscode/koroFileHeader/" class="sidebar-link">vscode插件之koroFileHeader</a></li></ul></section></li></ul> </aside> <main class="page"> <div class="theme-default-content content__default"><h1 id="js中防抖与节流的讲解与封装"><a href="#js中防抖与节流的讲解与封装" class="header-anchor">#</a> JS中防抖与节流的讲解与封装</h1> <p><strong>防抖：</strong> 当一直触发某个事件时，只有当停止触发一段时间后才会 执行该做的事情</p> <p><strong>节流：</strong> 当一直触发某个事件时，不会一直执行，而是按一定时间内有规律周期性的执行一次，直至停止触发。</p> <h2 id="防抖"><a href="#防抖" class="header-anchor">#</a> 防抖</h2> <p><strong>例1：</strong></p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token comment">//防抖</span>
<span class="token keyword">let</span> timer <span class="token operator">=</span> <span class="token keyword">null</span>
window<span class="token punctuation">.</span><span class="token function-variable function">onscroll</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>timer<span class="token punctuation">)</span> <span class="token punctuation">{</span>
  window<span class="token punctuation">.</span><span class="token function">clearTimeout</span><span class="token punctuation">(</span>timer<span class="token punctuation">)</span>
  <span class="token punctuation">}</span>
   timer <span class="token operator">=</span> window<span class="token punctuation">.</span><span class="token function">setTimeout</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
       console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">&quot;执行任务&quot;</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre></div><p>为了更方便的使用防抖方法，<strong>封装方法</strong>。</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">debounce</span><span class="token punctuation">(</span><span class="token parameter">func<span class="token punctuation">,</span> wait <span class="token operator">=</span> <span class="token number">300</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
 <span class="token keyword">let</span> timer <span class="token operator">=</span> <span class="token keyword">null</span>
 <span class="token keyword">return</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter"><span class="token operator">...</span>arg</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
   <span class="token keyword">if</span><span class="token punctuation">(</span>timer <span class="token operator">!==</span> <span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
     <span class="token function">clearTimeout</span><span class="token punctuation">(</span>timer<span class="token punctuation">)</span>
  <span class="token punctuation">}</span>
   timer <span class="token operator">=</span> <span class="token function">setTimeout</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  <span class="token function">func</span><span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> arg<span class="token punctuation">)</span>
       timer <span class="token operator">=</span> <span class="token keyword">null</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span> wait<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token comment">//创建函数 就是 上面 return 的函数</span>
<span class="token keyword">let</span> scrollHandler <span class="token operator">=</span> <span class="token function">debounce</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">e</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>e<span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">500</span><span class="token punctuation">)</span>
<span class="token comment">//无需传参时 可直接使用 因为 scrollHandler 就是一个函数</span>
window<span class="token punctuation">.</span>onscroll <span class="token operator">=</span> scrollHandler

<span class="token comment">//需要传参时</span>
<span class="token keyword">let</span> scrollHandler <span class="token operator">=</span> <span class="token function">debounce</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">e<span class="token punctuation">,</span>c</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>e<span class="token punctuation">,</span>c<span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">500</span><span class="token punctuation">)</span>
window<span class="token punctuation">.</span><span class="token function-variable function">onscroll</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token function">scrollHandler</span><span class="token punctuation">(</span><span class="token string">&quot;1&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;2&quot;</span><span class="token punctuation">)</span> <span class="token comment">//调用该函数</span>
<span class="token punctuation">}</span>
</code></pre></div><p><strong>有时我们希望函数能立即执行</strong>。因此添加是否立即执行的参数</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token comment">/**
* @param {function} func - 执行函数
* @param {number} wait - 等待时间
* @param {boolean} immediate - 是否立即执行
* @return {function}
*/</span>
<span class="token keyword">function</span> <span class="token function">debounce</span><span class="token punctuation">(</span><span class="token parameter">func<span class="token punctuation">,</span> wait <span class="token operator">=</span> <span class="token number">300</span><span class="token punctuation">,</span> immediate <span class="token operator">=</span> <span class="token boolean">false</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
   <span class="token keyword">let</span> timer <span class="token operator">=</span> <span class="token keyword">null</span>
<span class="token keyword">return</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter"><span class="token operator">...</span>arg</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
       <span class="token keyword">if</span><span class="token punctuation">(</span>timer <span class="token operator">!==</span> <span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token function">clearTimeout</span><span class="token punctuation">(</span>timer<span class="token punctuation">)</span>
      <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token keyword">if</span><span class="token punctuation">(</span>immediate<span class="token punctuation">)</span><span class="token punctuation">{</span>
           <span class="token function">func</span><span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> arg<span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
       timer <span class="token operator">=</span> <span class="token function">setTimeout</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
           <span class="token function">func</span><span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> arg<span class="token punctuation">)</span>
           timer <span class="token operator">=</span> <span class="token keyword">null</span>
      <span class="token punctuation">}</span><span class="token punctuation">,</span> wait<span class="token punctuation">)</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">//创建函数 就是 上面 return 得函数</span>
<span class="token keyword">let</span> scrollHandler <span class="token operator">=</span> <span class="token function">debounce</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">e</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>e<span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">500</span><span class="token punctuation">)</span>
<span class="token comment">//无需传参时 可直接使用 因为 scrollHandler 就是一个函数</span>
window<span class="token punctuation">.</span>onscroll <span class="token operator">=</span> scrollHandler

<span class="token comment">//需要传参时</span>
<span class="token keyword">let</span> scrollHandler <span class="token operator">=</span> <span class="token function">debounce</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">e<span class="token punctuation">,</span>c</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>e<span class="token punctuation">,</span>c<span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">500</span><span class="token punctuation">)</span>
window<span class="token punctuation">.</span><span class="token function-variable function">onscroll</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token function">scrollHandler</span><span class="token punctuation">(</span><span class="token string">&quot;1&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;2&quot;</span><span class="token punctuation">)</span> <span class="token comment">//调用该函数</span>
<span class="token punctuation">}</span>
</code></pre></div><!----> <h2 id="节流"><a href="#节流" class="header-anchor">#</a> 节流</h2> <p><strong>例：</strong></p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token comment">//节流</span>
<span class="token keyword">let</span> timer <span class="token operator">=</span> <span class="token keyword">null</span>
window<span class="token punctuation">.</span><span class="token function-variable function">onscroll</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
   <span class="token keyword">if</span><span class="token punctuation">(</span>timer <span class="token operator">===</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
       timer <span class="token operator">=</span> window<span class="token punctuation">.</span><span class="token function">setTimeout</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
           console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">&quot;执行任务&quot;</span><span class="token punctuation">)</span>
           timer <span class="token operator">=</span> <span class="token keyword">null</span>
      <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre></div><p>这样就会实现 没间隔 1秒 就执行一次任务，但是不足之处有两点</p> <ol><li>没法一开始就执行一下任务</li> <li>没法准确抓住最后停止时再执行一次任务</li></ol> <p><strong>解决问题：</strong></p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token comment">//节流</span>
<span class="token keyword">let</span> timer <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">,</span> last
window<span class="token punctuation">.</span><span class="token function-variable function">onscroll</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
   <span class="token keyword">const</span> now <span class="token operator">=</span> <span class="token operator">+</span><span class="token keyword">new</span> <span class="token class-name">Date</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
   <span class="token comment">//如果last存在 且当前时间小于 last + 延迟时间 即非执行任务 期间</span>
   <span class="token keyword">if</span> <span class="token punctuation">(</span>last <span class="token operator">&amp;&amp;</span> now <span class="token operator">&lt;</span> last <span class="token operator">+</span> <span class="token number">1000</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
       <span class="token function">clearTimeout</span><span class="token punctuation">(</span>timer<span class="token punctuation">)</span>
       timer <span class="token operator">=</span> <span class="token function">setTimeout</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">//保证最后一次执行任务 是 最终状态</span>
           console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">&quot;执行任务&quot;</span><span class="token punctuation">)</span>
      <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">300</span><span class="token punctuation">)</span> <span class="token comment">//停止触发 后300毫秒立即执行</span>
  <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
       <span class="token comment">//0秒的时候不执行任务 则加上这句判断 0+wait， 0 + 2*wait ... 执行任务</span>
       <span class="token keyword">if</span> <span class="token punctuation">(</span>last<span class="token punctuation">)</span> <span class="token punctuation">{</span>
      console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">&quot;执行任务&quot;</span><span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
       
       <span class="token comment">//0秒 0+wait， 0 + 2*wait ... 执行任务</span>
       console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">&quot;执行任务&quot;</span><span class="token punctuation">)</span>
       last <span class="token operator">=</span> now <span class="token comment">//将当前时间给 last 用来判断下一个周期</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre></div><p>这样即解决了上述问题，接下来就是封装起来</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token comment">/**
 * @param {function} func - 执行函数
 * @param {number} wait - 等待时间  默认 1000毫秒
 * @param {boolean} immediate - 是否立即执行 默认false
 * @param {number} stopTime - 停止触发后多少毫秒后 执行任务 默认300毫秒
 * @return {function}
 */</span>
<span class="token keyword">function</span> <span class="token function">throttle</span> <span class="token punctuation">(</span><span class="token parameter">func<span class="token punctuation">,</span> wait <span class="token operator">=</span> <span class="token number">1000</span><span class="token punctuation">,</span> immediate <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">,</span> stopTime <span class="token operator">=</span> <span class="token number">300</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
  <span class="token keyword">let</span> last<span class="token punctuation">,</span> timer
  <span class="token keyword">return</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter"><span class="token operator">...</span>arg</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">const</span> now <span class="token operator">=</span> <span class="token operator">+</span><span class="token keyword">new</span> <span class="token class-name">Date</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span>last <span class="token operator">&amp;&amp;</span> now <span class="token operator">&lt;</span> last <span class="token operator">+</span> wait<span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token function">clearTimeout</span><span class="token punctuation">(</span>timer<span class="token punctuation">)</span>
      timer <span class="token operator">=</span> <span class="token function">setTimeout</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token function">func</span><span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> arg<span class="token punctuation">)</span>
      <span class="token punctuation">}</span><span class="token punctuation">,</span> stopTime<span class="token punctuation">)</span>
    <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
      <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>immediate<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">if</span> <span class="token punctuation">(</span>last<span class="token punctuation">)</span> <span class="token punctuation">{</span>
          <span class="token function">func</span><span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> arg<span class="token punctuation">)</span>
        <span class="token punctuation">}</span>
      <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
        <span class="token function">func</span><span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> arg<span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
      last <span class="token operator">=</span> now
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">//创建函数 就是 上面 return 得函数</span>
<span class="token keyword">let</span> scrollHandler <span class="token operator">=</span> <span class="token function">throttle</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">e</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>e<span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">2000</span><span class="token punctuation">)</span>
<span class="token comment">//无需传参时 可直接使用 因为 scrollHandler 就是一个函数</span>
window<span class="token punctuation">.</span>onscroll <span class="token operator">=</span> scrollHandler

<span class="token comment">//需要传参时</span>
<span class="token keyword">let</span> scrollHandler <span class="token operator">=</span> <span class="token function">throttle</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">e<span class="token punctuation">,</span>c</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>e<span class="token punctuation">,</span>c<span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token number">2000</span><span class="token punctuation">,</span> <span class="token boolean">true</span><span class="token punctuation">)</span>
window<span class="token punctuation">.</span><span class="token function-variable function">onscroll</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token function">scrollHandler</span><span class="token punctuation">(</span><span class="token string">&quot;1&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;2&quot;</span><span class="token punctuation">)</span> <span class="token comment">//调用该函数</span>
<span class="token punctuation">}</span>
</code></pre></div><p><strong>这样防抖与节流的方法 就都好了。</strong></p></div> <footer class="page-edit"><!----> <!----></footer> <div class="page-nav"><p class="inner"><span class="prev">
      ←
      <a href="/JS/call-apply-bind/" class="prev">
        js中的call、apply和bind
      </a></span> <span class="next"><a href="/JS/tree-data/">
        JS中树形结构数据相关方法
      </a>
      →
    </span></p></div> </main></div><div class="global-ui"><div id="loading-mask"><div class="loading-wrapper"><span class="loading-dot loading-dot-spin"><i></i> <i></i> <i></i> <i></i></span></div></div><!----></div></div>
    <script src="/assets/js/app.36e8cb25.js" defer></script><script src="/assets/js/2.cd8e88cf.js" defer></script><script src="/assets/js/25.260c7616.js" defer></script>
  </body>
</html>
